Skip to content

Commit

Permalink
implement option_shutdown_anysegwit
Browse files Browse the repository at this point in the history
lightning/bolts#672

We check the received shutdown script against higher segwit versions and
accept closing to that script if option_shutdown_anysegwit has been
negotiated.
  • Loading branch information
bitromortac committed Oct 22, 2021
1 parent 9b28af2 commit cdac37e
Show file tree
Hide file tree
Showing 5 changed files with 56 additions and 8 deletions.
22 changes: 17 additions & 5 deletions electrum/lnpeer.py
Original file line number Diff line number Diff line change
Expand Up @@ -495,6 +495,9 @@ def close_and_cleanup(self):
self.lnworker.peer_closed(self)
self.got_disconnected.set()

def is_shutdown_anysegwit(self):
return self.features.supports(LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_OPT)

def is_static_remotekey(self):
return self.features.supports(LnFeatures.OPTION_STATIC_REMOTEKEY_OPT)

Expand Down Expand Up @@ -1692,11 +1695,20 @@ async def on_shutdown(self, chan: Channel, payload):
if their_upfront_scriptpubkey:
if not (their_scriptpubkey == their_upfront_scriptpubkey):
raise UpfrontShutdownScriptViolation("remote didn't use upfront shutdown script it commited to in channel opening")
# BOLT-02 restrict the scriptpubkey to some templates:
if not (match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_WITNESS_V0)
or match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2SH)
or match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2PKH)):
raise Exception(f'scriptpubkey in received shutdown message does not conform to any template: {their_scriptpubkey.hex()}')
else:
# BOLT-02 restrict the scriptpubkey to some templates:
# order by decreasing dust limit
if match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2PKH): # 546 sat
pass
if match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2SH): # 540 sat
pass
elif self.is_shutdown_anysegwit() and match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT): # 354 sat
pass
if match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_WITNESS_V0): # 294/330 sat
pass
else:
raise Exception(f'scriptpubkey in received shutdown message does not conform to any template: {their_scriptpubkey.hex()}')

chan_id = chan.channel_id
if chan_id in self.shutdown_received:
self.shutdown_received[chan_id].set_result(payload)
Expand Down
7 changes: 7 additions & 0 deletions electrum/lnutil.py
Original file line number Diff line number Diff line change
Expand Up @@ -1026,6 +1026,12 @@ class LnFeatures(IntFlag):
_ln_feature_contexts[OPTION_TRAMPOLINE_ROUTING_REQ] = (LNFC.INIT | LNFC.NODE_ANN | LNFC.INVOICE)
_ln_feature_contexts[OPTION_TRAMPOLINE_ROUTING_OPT] = (LNFC.INIT | LNFC.NODE_ANN | LNFC.INVOICE)

OPTION_SHUTDOWN_ANYSEGWIT_REQ = 1 << 26
OPTION_SHUTDOWN_ANYSEGWIT_OPT = 1 << 27

_ln_feature_contexts[OPTION_SHUTDOWN_ANYSEGWIT_REQ] = (LNFC.INIT | LNFC.NODE_ANN)
_ln_feature_contexts[OPTION_SHUTDOWN_ANYSEGWIT_OPT] = (LNFC.INIT | LNFC.NODE_ANN)

# temporary
OPTION_TRAMPOLINE_ROUTING_REQ_ECLAIR = 1 << 50
OPTION_TRAMPOLINE_ROUTING_OPT_ECLAIR = 1 << 51
Expand Down Expand Up @@ -1114,6 +1120,7 @@ def supports(self, feature: 'LnFeatures') -> bool:
| LnFeatures.PAYMENT_SECRET_OPT | LnFeatures.PAYMENT_SECRET_REQ
| LnFeatures.BASIC_MPP_OPT | LnFeatures.BASIC_MPP_REQ
| LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT | LnFeatures.OPTION_TRAMPOLINE_ROUTING_REQ
| LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_OPT | LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_REQ
)


Expand Down
3 changes: 2 additions & 1 deletion electrum/lnworker.py
Original file line number Diff line number Diff line change
Expand Up @@ -175,7 +175,8 @@ class ErrorAddingPeer(Exception): pass
| LnFeatures.OPTION_STATIC_REMOTEKEY_REQ\
| LnFeatures.GOSSIP_QUERIES_REQ\
| LnFeatures.BASIC_MPP_OPT\
| LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT
| LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT\
| LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_OPT\

LNGOSSIP_FEATURES = BASE_FEATURES\
| LnFeatures.GOSSIP_QUERIES_OPT\
Expand Down
12 changes: 10 additions & 2 deletions electrum/tests/test_transaction.py
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,8 @@
from electrum import transaction, bitcoin
from electrum.transaction import (convert_raw_tx_to_hex, tx_from_any, Transaction,
PartialTransaction, TxOutpoint, PartialTxInput,
PartialTxOutput, Sighash)
PartialTxOutput, Sighash, match_script_against_template,
SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT)
from electrum.util import bh2u, bfh
from electrum.bitcoin import (deserialize_privkey, opcodes,
construct_script, construct_witness)
Expand Down Expand Up @@ -78,6 +79,13 @@ def test_bool(self):


class TestTransaction(ElectrumTestCase):
def test_match_against_script_template(self):
script = bfh(construct_script([opcodes.OP_5, bytes(29)]))
self.assertTrue(match_script_against_template(script, SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT))
script = bfh(construct_script([opcodes.OP_NOP, bytes(30)]))
self.assertFalse(match_script_against_template(script, SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT))
script = bfh(construct_script([opcodes.OP_0, bytes(50)]))
self.assertFalse(match_script_against_template(script, SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT))

def test_tx_update_signatures(self):
tx = tx_from_any("cHNidP8BAFUBAAAAASpcmpT83pj1WBzQAWLGChOTbOt1OJ6mW/OGM7Qk60AxAAAAAAD/////AUBCDwAAAAAAGXapFCMKw3g0BzpCFG8R74QUrpKf6q/DiKwAAAAAAAAA")
Expand Down Expand Up @@ -927,7 +935,7 @@ class TestSighashTypes(ElectrumTestCase):
txin = PartialTxInput(prevout=prevout)
txin.nsequence=0xffffffff
txin.script_type='p2sh-p2wsh'
txin.witness_script = bfh('56210307b8ae49ac90a048e9b53357a2354b3334e9c8bee813ecb98e99a7e07e8c3ba32103b28f0c28bfab54554ae8c658ac5c3e0ce6e79ad336331f78c428dd43eea8449b21034b8113d703413d57761b8b9781957b8c0ac1dfe69f492580ca4195f50376ba4a21033400f6afecb833092a9a21cfdf1ed1376e58c5d1f47de74683123987e967a8f42103a6d48b1131e94ba04d9737d61acdaa1322008af9602b3b14862c07a1789aac162102d8b661b0b3302ee2f162b09e07a55ad5dfbe673a9f01d9f0c19617681024306b56ae')
txin.witness_script = bfh('56210307b8ae49ac90a048e9b53357a2354b3334e9c8bee813ecb98e99a7e07e8c3ba32103b28f0c28bfab54554ae8c658ac5c3e0ce6e79ad336331f78c428dd43eea8449b21034b8113d703413d57761b8b9781957b8c0ac1dfe69f492580ca4195f50376ba4a21033400f6afecb833092a9a21cfdf1ed1376e58c5d1f47de74683123987e967a8f42103a6d48b1131e94ba04d9737d61acdaa1322008af9602b3b14862c07a1789aac162102d8b661b0b3302ee2f162b09e07a55ad5dfbe673a9f01d9f0c19617681024306b56ae')
txin.redeem_script = bfh('0020a16b5755f7f6f96dbd65f5f0d6ab9418b89af4b1f14a1bb8a09062c35f0dcb54')
txin._trusted_value_sats = 987654321
#Output of Transaction
Expand Down
20 changes: 20 additions & 0 deletions electrum/transaction.py
Original file line number Diff line number Diff line change
Expand Up @@ -431,7 +431,24 @@ def is_instance(cls, item):
or (isinstance(item, type) and issubclass(item, cls))


class OPGeneric:
def __init__(self, matcher: Callable=None):
if matcher is not None:
self.matcher = matcher

def match(self, op) -> bool:
return self.matcher(op)

@classmethod
def is_instance(cls, item):
# accept objects that are instances of this class
# or other classes that are subclasses
return isinstance(item, cls) \
or (isinstance(item, type) and issubclass(item, cls))

OPPushDataPubkey = OPPushDataGeneric(lambda x: x in (33, 65))
OPPushDataAnySegwit = OPPushDataGeneric(lambda x: x in list(range(2, 40 + 1)))
OP_ANYSEGWIT_VERSION = OPGeneric(lambda x: x in [eval(f"opcodes.OP_{i}") for i in range(0, 16 + 1)])

SCRIPTPUBKEY_TEMPLATE_P2PKH = [opcodes.OP_DUP, opcodes.OP_HASH160,
OPPushDataGeneric(lambda x: x == 20),
Expand All @@ -440,6 +457,7 @@ def is_instance(cls, item):
SCRIPTPUBKEY_TEMPLATE_WITNESS_V0 = [opcodes.OP_0, OPPushDataGeneric(lambda x: x in (20, 32))]
SCRIPTPUBKEY_TEMPLATE_P2WPKH = [opcodes.OP_0, OPPushDataGeneric(lambda x: x == 20)]
SCRIPTPUBKEY_TEMPLATE_P2WSH = [opcodes.OP_0, OPPushDataGeneric(lambda x: x == 32)]
SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT = [OP_ANYSEGWIT_VERSION, OPPushDataAnySegwit]


def match_script_against_template(script, template) -> bool:
Expand All @@ -459,6 +477,8 @@ def match_script_against_template(script, template) -> bool:
script_item = script[i]
if OPPushDataGeneric.is_instance(template_item) and template_item.check_data_len(script_item[0]):
continue
if OPGeneric.is_instance(template_item) and template_item.match(script_item[0]):
continue
if template_item != script_item[0]:
return False
return True
Expand Down

0 comments on commit cdac37e

Please sign in to comment.